The present invention relates generally to roof insulation methods and more particularly to roof insulation in metal buildings.
Metal buildings of the type conventionally used for barns, workshops and numerous industrial applications have many advantages over wood buildings, including ease of construction and low maintenance costs. Because of the rising costs of energy in recent years, it has become increasingly necessary to provide more efficient methods of insulation for metal buildings.
Conventionally, insulation for the roof of a metal building is provided by placing a layer of rolled insulation across the top of the purlins or rafters of a building prior to installing the roof. The roof is then attached to the purlins through the insulation. A problem with this method of insulation has been that the insulation must be tightly compressed between the sheeting and purlins. Compression of the insulation causes it to become less efficient at reducing heat transfer and as a result, there is a significant heat loss from the building roof in the area of the purlins. Additionally, the insulation which is rolled out over the purlins must be of limited thickness even in the area between the purlins due to the fact that it must be sufficiently compressed in the area above the purlins to allow attachment of the roof sheeting. Attempts have been made to improve the heat loss characteristics of a roof by installing pan insulation which fills the entire void between the purlins and the roof sheeting. However, this pan insulation must be supported at its lower surface. Conventional systems available for providing lower surface support of the pan insulation are time consuming to install and quite expensive. Another major problem with existing methods of insulating metal buildings is that heat is lost through the metal roof purlins by conduction to the exterior surface and thereafter through radiation. The purlins are thus cooled to a temperature much lower than that of the air in the building which causes condensation from water vapor in the air to form on the purlin surfaces. Conventional methods of insulating do not provide a positive vapor barrier below the purlins and therefore condensation problems arise.
It can, therefore, be seen that a need exists for a support system which will support insulation placed between purlins which also may function to provide a positive vapor barrier below the roof purlins. To be cost effective the system must be easily installed and must have low material and labor costs.